Pain in the ball of the foot can have many different causes. When the pain is associated with joint inflammation, toe extension deformity, or ligament tearing at the base of the toe, or when there is a prominent bone causing a painful callus to form on the bottom of the foot, metatarsal surgery may be necessary to repair the damage and treat the pain if conservative measures fail to alleviate the condition.
The metatarsal are five long bones found in the mid-section of the foot and run to the base of the toes. The end of these bones makes up the ball of the foot. Their position relative to each other can be a source of foot pain, since a great deal of ground pressure travels across the ball of the foot as one walks. There is a natural arc to these bones, and if any one of them becomes too long or too short or is positioned too far upward or downward, then the natural pressure points of that arc will be disrupted. This may be due to injury, surgical changes, or even simply the position of the bones from birth. The result of the pressure change may be increased pressure under that bone or a bone adjacent to the abnormal metatarsal, which can lead to joint inflammation, stress fracture, and painful calluses.
Metatarsal surgery tries to address the abnormal pressure pattern by restoring a normal metatarsal arc. This can take the form of a procedure to raise a drooping metatarsal, or shorten a long metatarsal to make it more even with the surrounding shorter metatarsals. Lengthening procedures can also be done through a special technique to slowly stretch a bone out after a cut is made in it using a external distraction device connected outside the skin to pins the expanding bone ends. Because this is a lengthy process, it is more common for the adjacent longer bones to be shortened back to the level of a short metatarsal if at all possible. The typical procedure involves a cut through the neck of the bone, near its end. The bone end is then slid back, up, or a combination of the two directions to correct the bone position. The unstable bone end is then secured to the rest of the bone again with a screw or pin to hold it in place as it takes about 6 weeks to heal. The foot is secured in a pneumatic walking boot to reduce forefoot pressure while it heals. Another potential procedure that is considered is the outright removal of the metatarsal head in question. This is performed if there is specific abnormal pressure under that bone, and surgery to move the bone up or back is not feasible or appropriate. This is often performed in cases of severe callus pain in older patients, or in the case of a chronic diabetic sore on the bottom of the foot.
In general, the above procedures involve the 2nd, 3rd, and 4th metatarsals. The 1st metatarsal, found at the base of the big toe, has its own set of potential abnormalities, including bunions, big toe joint arthritis, and instability, and treatment is often specific to those conditions. The same can be said about the 5th metatarsal, which is involved in a Tailor's bunion and a special callus on the side of the foot. Treatment for these conditions are also specific to the condition, and don't really fall into the same category as the above listed procedures, except for the procedure that removes the metatarsal head outright.
Complication potential for these surgeries are typical for all foot and ankle procedures, and generally they heal well without issues. One consideration special to this type of surgery is the potential for a 'transfer lesion'. A transfer lesion can be an area of skin irritation, pain, or a callus that forms as a result of the pressure transferring from under the corrected metatarsal to the metatarsal next to it. In essence, this can result in the same condition that was treated in the first place, simply changing the location on the foot. To counter this, surgeons often will address several bones at the same time to ensure the pressure arc across the ball of the foot is even. Beyond this issue, metatarsal surgery is very successful for treating pain in the ball of the foot, and is relatively easy to recover from.